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use worklist algorithm to avoid stack overflow #1125

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2017-06-30 18:10:36 -07:00
parent 1f29cebd4d
commit c44c8284bd
2 changed files with 83 additions and 36 deletions
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116
src/smt/theory_seq.cpp
View file

@ -2863,77 +2863,121 @@ bool theory_seq::canonize(expr_ref_vector const& es, expr_ref_vector& result, de
return change;
}
expr_ref theory_seq::expand(expr* e0, dependency*& eqs) {
expr_ref theory_seq::expand(expr* e, dependency*& eqs) {
unsigned sz = m_expand_todo.size();
m_expand_todo.push_back(e);
expr_ref result(m);
while (m_expand_todo.size() != sz) {
expr* e = m_expand_todo.back();
result = expand1(e, eqs);
if (result.get()) m_expand_todo.pop_back();
}
return result;
}
expr_ref theory_seq::try_expand(expr* e, dependency*& eqs){
expr_ref result(m);
dependency* deps = 0;
expr_dep ed;
if (m_rep.find_cache(e0, ed)) {
if (m_rep.find_cache(e, ed)) {
eqs = m_dm.mk_join(eqs, ed.second);
result = ed.first;
return result;
}
else {
m_expand_todo.push_back(e);
}
return result;
}
expr_ref theory_seq::expand1(expr* e0, dependency*& eqs) {
expr_ref result(m);
dependency* deps = 0;
result = try_expand(e0, deps);
if (result) return result;
expr* e = m_rep.find(e0, deps);
expr* e1, *e2, *e3;
expr_ref arg1(m), arg2(m);
context& ctx = get_context();
if (m_util.str.is_concat(e, e1, e2)) {
result = mk_concat(expand(e1, deps), expand(e2, deps));
arg1 = try_expand(e1, deps);
arg2 = try_expand(e2, deps);
if (!arg1 || !arg2) return result;
result = mk_concat(arg1, arg2);
}
else if (m_util.str.is_empty(e) || m_util.str.is_string(e)) {
result = e;
}
else if (m_util.str.is_prefix(e, e1, e2)) {
result = m_util.str.mk_prefix(expand(e1, deps), expand(e2, deps));
arg1 = try_expand(e1, deps);
arg2 = try_expand(e2, deps);
if (!arg1 || !arg2) return result;
result = m_util.str.mk_prefix(arg1, arg2);
}
else if (m_util.str.is_suffix(e, e1, e2)) {
result = m_util.str.mk_suffix(expand(e1, deps), expand(e2, deps));
arg1 = try_expand(e1, deps);
arg2 = try_expand(e2, deps);
if (!arg1 || !arg2) return result;
result = m_util.str.mk_suffix(arg1, arg2);
}
else if (m_util.str.is_contains(e, e1, e2)) {
result = m_util.str.mk_contains(expand(e1, deps), expand(e2, deps));
arg1 = try_expand(e1, deps);
arg2 = try_expand(e2, deps);
if (!arg1 || !arg2) return result;
result = m_util.str.mk_contains(arg1, arg2);
}
else if (m_util.str.is_unit(e, e1)) {
result = m_util.str.mk_unit(expand(e1, deps));
arg1 = try_expand(e1, deps);
if (!arg1) return result;
result = m_util.str.mk_unit(arg1);
}
else if (m_util.str.is_index(e, e1, e2)) {
result = m_util.str.mk_index(expand(e1, deps), expand(e2, deps), m_autil.mk_int(0));
arg1 = try_expand(e1, deps);
arg2 = try_expand(e2, deps);
if (!arg1 || !arg2) return result;
result = m_util.str.mk_index(arg1, arg2, m_autil.mk_int(0));
}
else if (m_util.str.is_index(e, e1, e2, e3)) {
result = m_util.str.mk_index(expand(e1, deps), expand(e2, deps), e3);
arg1 = try_expand(e1, deps);
arg2 = try_expand(e2, deps);
if (!arg1 || !arg2) return result;
result = m_util.str.mk_index(arg1, arg2, e3);
}
else if (m.is_ite(e, e1, e2, e3)) {
if (ctx.e_internalized(e) && ctx.e_internalized(e2) && ctx.get_enode(e)->get_root() == ctx.get_enode(e2)->get_root()) {
result = expand(e2, deps);
result = try_expand(e2, deps);
if (!result) return result;
add_dependency(deps, ctx.get_enode(e), ctx.get_enode(e2));
}
else if (ctx.e_internalized(e) && ctx.e_internalized(e2) && ctx.get_enode(e)->get_root() == ctx.get_enode(e3)->get_root()) {
result = expand(e3, deps);
result = try_expand(e3, deps);
if (!result) return result;
add_dependency(deps, ctx.get_enode(e), ctx.get_enode(e3));
}
else {
literal lit(mk_literal(e1));
literal lit(mk_literal(e1));
#if 0
expr_ref sk_ite = mk_sk_ite(e1, e2, e3);
add_axiom(~lit, mk_eq(e2, sk_ite, false));
add_axiom( lit, mk_eq(e3, sk_ite, false));
result = sk_ite;
expr_ref sk_ite = mk_sk_ite(e1, e2, e3);
add_axiom(~lit, mk_eq(e2, sk_ite, false));
add_axiom( lit, mk_eq(e3, sk_ite, false));
result = sk_ite;
#else
switch (ctx.get_assignment(lit)) {
case l_true:
deps = m_dm.mk_join(deps, m_dm.mk_leaf(assumption(lit)));
result = expand(e2, deps);
break;
case l_false:
deps = m_dm.mk_join(deps, m_dm.mk_leaf(assumption(~lit)));
result = expand(e3, deps);
break;
case l_undef:
result = e;
m_reset_cache = true;
TRACE("seq", tout << "undef: " << result << "\n";
tout << lit << "@ level: " << ctx.get_scope_level() << "\n";);
break;
}
switch (ctx.get_assignment(lit)) {
case l_true:
deps = m_dm.mk_join(deps, m_dm.mk_leaf(assumption(lit)));
result = try_expand(e2, deps);
if (!result) return result;
break;
case l_false:
deps = m_dm.mk_join(deps, m_dm.mk_leaf(assumption(~lit)));
result = try_expand(e3, deps);
if (!result) return result;
break;
case l_undef:
result = e;
m_reset_cache = true;
TRACE("seq", tout << "undef: " << result << "\n";
tout << lit << "@ level: " << ctx.get_scope_level() << "\n";);
break;
}
#endif
}
}

3
src/smt/theory_seq.h
View file

@ -462,7 +462,10 @@ namespace smt {
expr_ref canonize(expr* e, dependency*& eqs);
bool canonize(expr* e, expr_ref_vector& es, dependency*& eqs);
bool canonize(expr_ref_vector const& es, expr_ref_vector& result, dependency*& eqs);
ptr_vector<expr> m_expand_todo;
expr_ref expand(expr* e, dependency*& eqs);
expr_ref expand1(expr* e, dependency*& eqs);
expr_ref try_expand(expr* e, dependency*& eqs);
void add_dependency(dependency*& dep, enode* a, enode* b);
void get_concat(expr* e, ptr_vector<expr>& concats);